Fire-cracked rock

In archaeology, fire-cracked rock, or FCR, is rock of any type that has been altered and split by deliberate heating. It is a feature of many archaeological sites, particularly in the south-central United States. In many cases, fire-cracked rock results when stones were used to line hearths or were heated to provide a longer-lasting heat-source (similar to a modern hot water bottle).

In other cases, fire-cracked rock results from stone being used to heat or boil water; the stones were heated and dropped directly into water held in containers made of skin or pottery. This use has led fire-cracked rocks to be called 'pot-boilers' in Britain.

Central Texas in the United States in particular is well-known archaeologically for its burned rock middens, which are piles of fire-cracked rock—often exceeding several tons of material. These represent the remains of earth ovens used in cooking sotol bulbs and other plants during prehistoric times. In Britain these features are referred to as 'burnt mounds'.